In Belgium, students of Turkish and North African descent express optimistic attitudes toward education. However, these attitudes conflict with their achievement results, as many underachieve compared to their peers of Belgian descent. Mickelson’s work discusses this attitude–achievement paradox in the United States. In the current study, we use Mickelson’s framework to investigate the attitude–achievement paradox in Belgium. Using quantitative and qualitative research methods, we find that students of Turkish, North African and Belgian descent believe in the importance of education to get ahead in society, holding optimistic abstract attitudes. Students of Turkish and North African descent hold more optimistic attitudes than students of Belgian descent. However, these abstract attitudes toward education do not translate into ethnic minority students’ concrete attitudes toward education, which depend mainly on the socioeconomic background of the student. Students with a low socioeconomic background are much more pessimistic than students with a high socioeconomic background. Concrete attitudes influence the achievement of students of Belgian descent; this is not the case for students of Turkish and North African descent. Qualitative research shows that to understand the interpretation of concrete school attitudes and its relationship with achievement results, we need to consider students’ definitions of success, frames of reference and perceived constraints and opportunities.